To view the keys available for GRIB1 and GRIB2 have a look at the parameter database at http://apps.ecmwf.int/codes/grib/
Similarly for the file file2.grib2
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To list the GRIB messages in msl.grib1, use:
The file contains mean sea-level pressure (shortName=msl) from the ECMWF ENS control forecast (dataType=cf) for 6-hourly steps from 6 to 24 hours for dataDate=20190201. The messages are encoded in GRIB edition 1.
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To list the nearest points to ECMWF (Lat 51.42 N, Lon 0.95 W) use 4 of 4 messages in msl.grib1 4 of 4 total messages in 1 files Input Point: latitude=51.42 longitude=-0.95 Grid Point chosen #2 index=156197 latitude=51.38 longitude=359.03 distance=4.79 (Km) Other grid Points - 1 - index=156198 latitude=51.38 longitude=359.35 distance=21.64 (Km) - 2 - index=156197 latitude=51.38 longitude=359.03 distance=4.79 (Km) - 3 - index=155082 latitude=51.52 longitude=359.35 distance=23.65 (Km) - 4 - index=155081 latitude=51.52 longitude=359.03 distance=11.09 (Km) Note we specify the longitude of 0.95 W with -0.95 ! The nearest grid point is at latitude=51.38 longitude=359.03 (=0.97 W) and is 4.79 km from ECMWF. msl.grib1 stepRange value 6 98263.5 12 98621.1 18 99085.2 24 99593.2 4 of 4 messages in msl.grib1 4 of 4 total messages in 1 files Input Point: latitude=51.42 longitude=-0.95 Grid Point chosen #2 index=156197 latitude=51.38 longitude=359.03 distance=4.79 (Km) Other grid Points - 1 - index=156198 latitude=51.38 longitude=359.35 distance=21.64 (Km) - 2 - index=156197 latitude=51.38 longitude=359.03 distance=4.79 (Km) - 3 - index=155082 latitude=51.52 longitude=359.35 distance=23.65 (Km) - 4 - index=155081 latitude=51.52 longitude=359.03 distance=11.09 (Km)
msl.grib1 stepRange value1 value2 value3 value4 6 98236.5 98263.5 98293.5 98319.2 12 98596.1 98621.1 98644.4 98666.1 18 99043 99085.2 99074.5 99116 24 99547 99593.2 99561.5 99612.2 4 of 4 messages in msl.grib1 4 of 4 total messages in 1 files Input Point: latitude=51.42 longitude=-0.95 Grid Point chosen #2 index=156197 latitude=51.38 longitude=359.03 distance=4.79 (Km) Other grid Points - 1 - index=156198 latitude=51.38 longitude=359.35 distance=21.64 (Km) - 2 - index=156197 latitude=51.38 longitude=359.03 distance=4.79 (Km) - 3 - index=155082 latitude=51.52 longitude=359.35 distance=23.65 (Km) - 4 - index=155081 latitude=51.52 longitude=359.03 distance=11.09 (Km) To specify the land-sea mask, use: msl.grib1 stepRange value 6 98263.5 12 98621.1 18 99085.2 24 99593.2 4 of 4 messages in msl.grib1 4 of 4 total messages in 1 files Input Point: latitude=51.42 longitude=-0.95 Grid Point chosen #2 index=156197 latitude=51.38 longitude=359.03 distance=4.79 (Km) Mask values: - 1 - index=156198 latitude=51.38 longitude=359.35 distance=21.64 (Km) value=1.00 - 2 - index=156197 latitude=51.38 longitude=359.03 distance=4.79 (Km) value=0.99 - 3 - index=155082 latitude=51.52 longitude=359.35 distance=23.65 (Km) value=0.99 - 4 - index=155081 latitude=51.52 longitude=359.03 distance=11.09 (Km) value=0.99 Here the mask value at the end of the line showing the four nearest grid points indicates which are land points: Land points have mask ≥ 0.5; sea points have mask<0.5. This works in the same way for msl.grib2. Note that you can pass the land-sea mask file as either GRIB edition 1 or GRIB edition 2. |